This invention relates to household laundry processes for combined washing and bleaching of cotton fabrics, and to simultaneous removal of stains and fugitive dyes.
U.S. Pat. No. 3,927,967 granted to Speakman on Dec. 23, 1975 related to a household washing and bleaching process for cotton fabrics utilizing photoactivating compounds, principally sulfonated zinc phthalocyanine, in the presence of visible light and atmospheric oxygen. Japanese Patent application OPI No. 50-113,479 assigned to The Proctor & Gamble Company, laid open to the public on Sept. 5, 1975, teaches the use of specific mixtures of sulfonated zinc phthalocyanine species, principally tri- and tetra-sulfonates, as preferred bleach photoactivators. In each of the foregoing references the detergent compositions utilizing sulfonated zinc phthalocyanine contained both organic surfactant and alkaline builder salt.
Belgian Pat. No. 840,348 invented by Wiers, granted on Oct. 4, 1976 discloses the use of zinc phthalocyanine tri- and tetra-sulfonates as bleach photoactivators in unbuilt liquid detergent compositions.
British Pat. No. 1,372,036 invented by Speakman and available to the public on Oct. 30, 1974 describes a washing machine provided with a source of visible light which irradiates wash liquor containing phthalocyanine photoactivator and fabrics.
U.S. Pat. Nos. 2,951,797; 2,951,798; 2,951,799 and 2,951,800, assigned to Monsanto Chemical Company and issued on Sept. 6, 1960 describe certain porphines as catalysts for the photo-oxidation of olefins.
It has now been found that certain other species of photoactivators perform a cotton fabric bleaching function similar to that of sulfonated phthalocyanines in the presence of visible light and atmospheric oxygen, and indeed under some circumstances are superior thereto. These other photoactivators provide in fact not only stain removal but also improved whitening of the fabrics in two other respects: the first of these is an improvement in the general whiteness of the fabrics, which is often referred to as whiteness maintenance; this improvement is not however accomplished in the ordinary way by reducing the reprecipitation of dirt upon cleaned fabrics, but rather by oxygen bleaching of the overall fabric discoloration that is often present in soiled fabrics even after washing with ordinary detergent compositions.
The second respect in which whiteness can be improved by the compositions of this invention is in the removal of so-called fugitive dyes--the tendency of some colored fabrics to release dye into the laundering solutions, which dye is then transferred during laundering onto other fabrics being washed therewith. Dye transfer removal using peroxy acids together with chemical activators is the subject of U.S. Pat. No. 3,822,114 granted on July 2, 1974 to Montgomery and Jones and commonly assigned U.S. patent application Ser. No. 583,383 filed on June 3, 1975 (Montgomery). Dye transfer removal using peroxy compounds such as hydrogen peroxide or sodium perborate catalyzed by porphines and phthalocyanines chelated with iron, and only iron, is the subject of commonly assigned U.S. patent application Ser. No. 697,006 filed on June 17, 1976 (Johnson and Tate).
The foregoing objects of this invention can be conveniently accomplished by a washing process which is followed by drying out-of-doors, especially in direct sunlight as on a clothesline. The common procedure of soaking fabrics in the wash/bleach solution prior to the actual washing process is an especially effective way to accomplish the objects of this invention.